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Prenatal Screening and Diagnosis

If you are considering undergoing prenatal screening, or if you have received a prenatal diagnosis and are looking for immediate support, please click here here for a list of support resources.

If your physician is recommending a cell-free DNA test, or a so-called non-invasive prenatal screening test such as MaterniT21, Harmony, Panorama, or Verify, you should read this first.

Many doctors do not understand how to communicate the results of cell-free DNA tests, and patients are sometimes led either by their physician or the manufacterer's marketing to believe that these tests can provide a definitive result when, in fact, they are only screening tests.

Prenatal Screening vs. Prenatal Diagnosis

It is important to understand that prenatal screening tests do not provide a diagnosis. Tests like those mentioned below can only give women a percentage of likelihood that they are carrying a child with a genetic difference like Down syndrome. If a prenatal screening test indicates the possibility of a genetic condition, many doctors will recommend that their patients go on to have an invasive diagnostic test like an amniocentesis or CVS to confirm the result.

Prenatal Screening

Many women first learn they may be carrying a child with Down syndrome, or some other genetic condition, through routine prenatal screening tests. In 2007, the American College of Obstetricians and Gynecologists (ACOG) revised its recommendations to suggest that all pregnant women receive fetal chromosomal screening in their first trimester, not just those considered at risk because of advanced maternal age or some other reason. 80% of children born with Down syndrome are born to women under 35.

Many different opinions exist regarding the importance of prenatal screening. Since, at present, there is no prenatal treatment for Down syndrome, or other genetic intellectual disability, these tests can only inform the family that their baby may have a genetic condition like Down syndrome. Ideally, parents will use the information to prepare themselves emotionally for delivery, and some may even feel that they need to arrange for an adoption. Too often, parents feel pressured by their medical provider or their family and friends to end their pregnancy. It is critically important that before any decision is made, families receive factual, up-to-date, information about all the outcomes of raising a child with a disability. Most families, when properly informed, realize that there are challenges to raising any child, and that children with disabilities can bring a special joy into the family dynamic.

If you have had a prenatal screening test that indicates a possibility that you are carrying a child with Down syndrome, or some other genetic intellectual disability, it is important that you find good resources to assist you right away. This can be a very lonely and challenging time, but there is plenty of help available. Many families who have children with genetic differences, such as Down syndrome, are anxious to share their stories with others.

For a list of resources, click here

First Trimester Prenatal Screening

Initial screening for Down syndrome, trisomy 18, and neural tube defects (such as spinal bifida and anencephaly) is recommended between the 11th and 14th weeks of pregnancy. A nuchal translucency screen (NTS) is performed to measure the thickness of the nuchal fold at the back of the neck. A blood test also measures the level of pregnancy-associated plasma protein (PAPPA). A thicker than normal nuchal fold, and lower than normal levels of PPAPA are possible, but not definitive, indicators of Down syndrome.

It is also possible that your physician will recommend a cell-free DNA test, or a so-called non-invasive prenatal test (NIPT). These recently developed tests, going by the brand names like MaterniT21, Panorama, Verify, and Harmony, are able to identify the presence of "cell-free DNA" from the fetus in the mother's blood as early as 10 weeks. Manufacturers claim the accuracy of these tests far exceeds that of any other non-invasive test previously available. They claim to be 99% to 100% accurate for women considered to be at high risk, i.e., over 35 or having previously delivered a child with a genetic abnormality, but these claims have been disputed. In addition to Down syndrome, these tests can also identify the possibility of trisomy 18 and 13, and some x-linked chromosomal abnormalities. The newest generation of these tests also claim to screen for Prader Willi/Angleman syndrome, DiGeorge syndrome, cri-du-chat, and 1p36 deletion syndrome, although the American Congress of Obstetricians and Gynecologists (ACOG) recommend against their use for this purpose. See ACOG's Practice Advisory on cell-free DNA screening for the most current recommendations. 

Once again, it is important to understand the difference between prenatal screening tests, and diagnostic tests that provide certainty that the child carries a genetic disability. Amniocentesis and chorionic villus sampling (CVS) are still the only approved diagnostic tests that are able to confirm the suspicion that a child will have a genetic difference.

Second Trimester Prenatal Screening

Between 15 and 22 weeks, additional testing is recommended. A Prenatal Risk Quad Screen is conducted to measure the level of 4 blood factors:

  • Alpha-fetoprotein (AFP)
  • Unconjugated estriol (UE)
  • Human chorionic gonadotropin (hCG)
  • Inhibin-A

The above first and second trimester tests are screening tests only. If they indicate the possibility a fetus has a chromosomal abnormality, physicians will recommend an invasive test before confirming the disability. Invasive tests are chorionic villus sampling (CVS) usually done between 10 and 13 weeks, or an amniocentesis which may be done between 15 and 22 weeks. Both of these invasive tests run a small risk of causing a miscarriage.

What To Do

We naturally expect pregnancy and birth to be a joyful time, filled with anticipation of a new life coming into the world to delight parents, family, and friends. Feelings of sadness, fear, and grief are a natural consequence of receiving the unanticipated news that your child will have a disability.

News of an unanticipated prenatal diagnosis brings with it an overload of information and opinions from your doctor and others who mean well, but who are often insensitive to the emotional distress you are experiencing. At these times the medical world can easily cause us to feel distanced from our own humanity - and from the humanity of our child. It is very important to retain perspective. Your child is no less a human person worthy of your love, post diagnosis, than he or she was before. A well known disabilities rights activist once said that the only thing a prenatal diagnosis can provide is a glimpse of who a child will become. Stop "googling" all the possible consequences, and just reflect on that simple fact. In the end, parental love has a way of overcoming the challenges that raising children present, including the challenges of disability. Many parents fear that their typical children will grow to no longer love them. That is NEVER a concern with a child with Down syndrome!

Before any decisions are made, it is important to distance yourself from the many competing voices around you, and to look at the lives of those who have had children with disabilities. By far, most have a deep love for their children - in fact, a depth of love they never knew could be possible. Research has shown than families who have children with Down syndrome, and other disabilities, are very happy. Yours will be too. You just have to give yourself time to move past your sorrow, and regain the anticipation of your child's birth. Life teaches us over and over again that sorrow and grief are passing emotions that heal in time. When your beautiful little baby is born and you hold him or her in your arms for the first time, the sorrow will pass. Parental love is an amazing thing. No one should risk losing the opportunity to experience it because of fear.

Please click here for a list of resources that can assist you as you search for clear and balanced information, and as you prepare for the birth of your child.

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